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About Pancho

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  • Name Tom
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  1. Well, if you want to melt something in H16 and it turns into a liquid it shouldn't deform before changing from its solid state into a liquid one. The way to do this a.f.a.i.k. is to use high viscosity and then change it to something lower.
  2. Am I the only one who seems to experience flip fluid movement due to surface tension on high viscosity fluids? Viscosity is set to 100.000, object size about 5cm (0.05 units) and tension is set to 1. The details disappear rather quickly and the surface gets smoother. THis shouldn't happen with such a high viscosity. Can I override the surface tension per particle, since the viscosity changes on a per particle basis? H16 here with the new surface tension in the solver. Cheers Tom
  3. I just mailed SideFx. Hopefully they take a look at this thread. Would be very nice.
  4. Ahh! So, what do we do about it? Use the grain solver? Is FEM the wrong approach for this kind of softbody sim?
  5. O.k., changed the scene slightly to make it quicker in terms of intercolission. Please set frame distance in the solid object back to 10 so that there are more eyes. What I noticed is that potentialdensity is rising as soon as the spheres pile up. I guess that's the "stored" energy. The spring, which gets more and more under pressure and want's to release it energy into kinetic energy, movement. While this might be right from a technical viewpoint, it seems to collide with what we expect to happen. Actually I would expect this material not to be a spring. While it might be able to store some energy, at a certain point there's no way to increase the potential energy. There would be a force in the sphere preventing the spring to get loaded anymore, but keep it at a certain threshold. Sounds a bit funky, but hey, I hate interpenetrations and strange sim behaviour. : ) flask.v4.Odforce.FF.hiplc
  6. No, I don't want to plastic the object. THat would totally change its behaviour look. I want to crop the forces above a level which might be the reason for the interpenetration. At one point there wouldn't be a difference if there are 4 spheres above the lowest sphere or twenty, since the force doesn't increase. @pskull: Saw the settings the first time and enabled them in the FemAtt.hip. Seems to give a good indication of what's going on. I just guess that setting them manually won't change a thing. Looks more like they are telling you what forces are happening at the moment, or do I miss something?
  7. Searched the web for some hours now. Looks like GrowFx for MAx seems to be one of the best tools to do this kind of stuff, but I just cancelled my Autodesk maintenance (Maya) for good. So no chance to get on this kind stuff. Apart from that I would like to keep it in H. Any idea what GrowFx is based on? The idea behind it? The downside of l-systems seems to be that they aren't aware of light and space. So the growth is purely mathematical, while in nature some leaves or twigs would never grow because of its surrounding companions and the shadow they cast.
  8. In a way it feels like RealFlow 10 years ago. Everybody tells you that this is the best software for water out there, but as soon as you tried to simulate water, nobody could tell you the "correct" settings for water. At best you could get an answer which sounded like "The setting's depend on what you want to achieve". Well, back then and now this answer has to components. On one hand it might be true to the extent that you are faking stuff and any way is good, as long as you get away with it visually. On the other hand it's been bu..sh.., since the water in my glass doesn't change its specific weight nor viscosity, depending on how I want to drink it. For trees and plants the feeling is a bit the same. There are packages out there like SpeedTree which are way overpriced and feel outdated. If you look at most examples they look kind of not soooo great, but then you look at archviz images which nail it. No idea where these trees come from. I guess H would be one of the most versatile solutions to create trees and looking at l-systems makes you hungry, but so far I haven't found real proof of concepts with l-systems in a way that there are settings available which deliver what you could expect. The presets are, well, presets. Nothings fancyful. And taking of a year from real life and studying l-systems doesn't sound so fancyful either. In all posts so far people point you to websites with material on plant growth, some of them roughly connected to l-systems. But none giving you a real insight how to recreate trees or plants in H. Rohan's videos and the one from CmiVfx seem to be the best available. There's also the way of using space colonisation. And then you look at the 10 year old stuff from Arkadiusz Rekita and realize that this hasen't been topped so far (as far as I know). What's the current state of the art way/program to create plants for usage in H? Curious... : ) Thanks for your input in advance! Tom
  9. Looked at your scene, but I'm not sure whether that is what I've meant. You are defining SHAPESTIFFNESS, but that's more or less just an attribute of the object, e.g. softer or harder (marshmallow vs rubber). As far as I can predict, this won't change the intercolission behaviour in the sim (the interpenetration). I expect the penetration to happen because of forces piling up in the tetrahedralized mesh to such an account, that the colission detection can't avoid interpenetration anymore. I thought there is a way to check the forces inside the mesh and if the force (which will be a vector, the force amount its length) is abouve a threshold then clamp it at this point. I expect the penetration to stop because of this. If you can't push harder than with a certain force, things shouldn't break. P.S.: In the attributecreate node's group settings, where do the numbers come from (1-2 5-6 ....)? Did Houdini create them or you?
  10. Good points!
  11. We should bring an employee of SFX into the discussion to get some decent explanations. Would be a pitty if this doesn't end with an "Ahhhhh!" moment. Not to be confused with "Aaargh!".
  12. Didn't have the chance to open the scene yet, but I'd like to check whether there's a way to control the maximum forces of the tetrahedal mesh inside of the spheres.
  13. P.S.: Is it the force which tries to reestablish the original form of the geometry? How can this force be cropped? Something like a maximum value. Even a marshmallow tries to get back in its original shape once deformed. But its force is small, so it takes a lot of time. With the spheres it should be the same.
  14. The point is how to avoid the "stored" force. An apple in a bowl of apples, even on the lowest level won't jump out of the bowl at any given moment. The pressure in the glass example should solely be made up out of the gravity force and the weight from the spheres ontop of it. This should never add up to any ridiculous force which make the sim go bonkers. So why do the shperes on the lowest level in the flask still penetrate each other? Seems that the structure inside of the mesh stores the force which should actually be destroyed by friction and generation of warmth by deforming the objects. How would one do this???
  15. Nice work, Johnny! But your scene suffers from the same problems at the end (lower left). My objects were all created on the first frame without interpenetrating each other. That CAN'T be the reason for the interpenetration later. At least not alone.